1. Field
This disclosure relates to wireless energy transfer, methods, systems and apparati to accomplish such transfer, and applications.
2. Description of the Related Art
Energy or power may be transferred wirelessly using a variety of techniques as detailed, for example, in commonly owned U.S. patent application Ser. No. 12/789,611 published on Sep. 23, 2010 as U.S. Pat. Pub. No. 2010/0237709 and entitled “RESONATOR ARRAYS FOR WIRELESS ENERGY TRANSFER,” and U.S. patent application Ser. No. 12/722,050 published on Jul. 22, 2010 as U.S. Pat. Pub. No. 2010/0181843 and entitled “WIRELESS ENERGY TRANSFER FOR REFRIGERATOR APPLICATION” the contents of which are incorporated in their entirety as if fully set forth herein. Prior art wireless energy transfer systems have been limited by a variety of factors including concerns over user safety, low energy transfer efficiencies and restrictive physical proximity/alignment tolerances for the energy supply and sink components.
One particular challenge in wireless energy transfer is control and tuning of the resonator structures and the power source. Other resonators, temperature, extraneous objects, and the like may affect the parameters of the resonators. The impedance, resonant frequency, loading conditions, and/or parameters of electrical components, and the like, may fluctuate during operation of the wireless energy transfer system. For example, a large conducting object brought close to a resonator may detune the resonator from its nominal resonant frequency, which detuning may affect the efficiency of wireless power transfer and may also affect the efficiency and amount of power transferred from the power source to the resonator.
In some embodiments parameters of the resonator, power source, and the like may need to be changed or tuned to control the operating point of the resonator or the system. For example, the resonant frequency of a resonator may need to be periodically changed to match the frequencies of nearby resonators that may be tuned to different frequencies. Changing the resonant frequency of a wireless source may require changes to the operating parameters of the power source to maintain high or optimum efficiency and power.
Therefore a need exists for methods and designs for tuning components of a wireless energy transfer system.